Embodiments of the present invention relate to an array substrate, a manufacturing method thereof and an organic light-emitting diode (OLED) display device.
OLED is considered to be one of the most important display technologies in the future due to the advantages of simple manufacturing process, low cost, free adjustment of emission colors within visible regions, large scale, flexible bending and the like. More particularly, the power efficiency of a white OLED (WOLED) has exceeded 60 lm/W and the service life of the WOLED has reached 20,000 hours or more, greatly promoting the development of the WOLED.
FIG. 1 is a schematic structural view of the traditional OLED array substrate, which specifically illustrates a structure of a pixel unit. The structure comprises (from bottom to top): a first gate electrode 2, a second gate electrode 2′ and gate lines (not illustrated in the figure) formed on a substrate 1, a gate insulating layer 3 formed on the first gate electrode 2, the second gate electrode 2′ and the gate lines, a first active layer 4 and a second active layer 4′ formed on the gate insulating layer 3, an insulating interlayer 5 formed on the first active layer 4 and the second active layer 4′, a first source-drain layer 6 (including a first source electrode and a first drain electrode) and a second source-drain layer 6′ (including a second source electrode and a second drain electrode) formed on the insulating interlayer 5, and a passivation layer 7 formed on the first source-drain layer 6 and the second source-drain layer 6′. The first gate electrode 2, the gate insulating layer 3, the first active layer 4, the insulating interlayer 5 and the first source-drain layer 6 constitute a switch thin-film transistor (switch TFT); the second gate electrode 2′, the gate insulating layer 3, the second active layer 4′, the insulating interlayer 5 and the second source-drain layer 6′ constitute a drive thin-film transistor (drive TFT). The passivation layer 7, a color filter 9, a resin layer 10, a first electrode 11 of an OLED, a pixel defining layer 12, an organic emission layer 13, and a second electrode 14 of the OLED are disposed above the first source-drain layer 6 and the second source-drain layer 6′ in sequence. The first electrode 11 is a transparent electrode, and light emitted by the organic emission layer is emitted after running through the first electrode and various layers under the first electrode. The OLED is disposed in a pixel region of the pixel unit (in general, a display area of the pixel unit, except for a TFT).
In the structure, as illustrated by dotted lines in FIG. 1, a storage capacitor is formed between the second gate electrode 2′ and the second source-drain layer 6′. An equivalent circuit diagram of the pixel unit is as illustrated in FIG. 2, in which Cs refers to the storage capacitor. As the WOLED requires a large driving current, a WOLED display device has large power consumption. In order to reduce the power consumption, a structure of the storage capacitor is formed on the substrate. The storage capacitor has the function of supplying one part of driving current for the WOLED in such a way that the driving current supplied by an electric power source can be correspondingly reduced, and hence the power consumption can be reduced. However, it can be seen from FIG. 1 that as two insulating layers are interposed between the second gate electrode 2′ and the drain electrode of the second source-drain layer 6′, the distance is large and the capacitance is small.